Biographical Memoir of Sir Humphry Davy. IT 



to the highest generalities, he took into account nothing in na- 

 ture but oxygen and unknown bases ; varying even his explana- 

 tions, as in algebra, in which a diversity of forms may lead to 

 the same result, he inquired whether hydrogen might not be the 

 principle of metallization, and whether oxides might not be re- 

 duced to combinations of bases with water, thus reverting, so to 

 speak, to the ancient hypothesis of phlogiston, under another 

 form. This tendency may be observed in many other of Mr 

 Davy's memoirs, and perhaps he may be suspected in this of a 

 little national jealousy. But although unsuccessful in over- 

 throwing the French theory of combustion, he adduced at least 

 such a striking exception, that instead of longer retaining the 

 character of a general explanation, it became applicable only to 

 particular cases of phenomena which required an explanation of 

 a more elevated nature ; and this forms the third and most im- 

 portant of his discoveries. It was already known by the expe- 

 riments of Bertholet, that sulphuretted hydrogen, which does 

 not contain oxygen, acts like an acid ; oxygen, therefore, is not 

 always the principle of acidity. On the other hand, the experi- 

 ments of Mr Davy went to prove that it is the principle of alca- 

 linity as well as of acidity, and thus its name was not justified 

 by its nature. It was soon to be shewn that hydrogen has the 

 power of producing acids, not less than oxygen. 



For a long time chemists had attempted in vain to discover 

 the base of muriatic acid ; but after the explanations proposed 

 by Bertholet, they supposed that this other acid, so cele- 

 brated for the uses to which it is apphed in the arts, and which 

 is obtained by causing muriatic acid to pass over oxide of man- 

 ganese, and named dephlogisticated muriatic acid by Steele 

 its discoverer, resulted from the combination of muriatic acid 

 with oxygen of the oxide ; it was consequently named oxyge- 

 nated muriatic acid, and nothing appeared more simple than to 

 extract from it the muriatic acid, by depriving it of this oxy- 

 gen with which it was believed to be surcharged. MM. Gay- 

 Lussac and Thenard attempted it, but could never succeed with- 

 out the addition of water or at least of hydrogen. This pheno- 



monia. 2d, On sulphur and phosphorus. 3d, On carbonaceous matter. 

 4th, Muriatic acid. Rot/. Soc. Lond. 2d February and 16th March 1809. 

 Phil. Trans, vol. xcix. p. 450. Biblioth. BriU voL xliv. p. 42. 



VOL. XV. NO. XXIX.— JULY 1833. B 



